Pluto’s atmosphere: Poisonous, thin, comet-like (Discovery News)

(Click image for a larger view.) Artist's impression of Pluto's huge atmosphere of carbon monoxide. The Sun appears at the top, as seen in the ultra-violet radiation that is thought to force some of the dramatic atmospheric changes. Pluto's largest moon, Charon, is seen to the lower right. Credit: P.A.S. Cruickshank.

Pluto’s planetary status was rescinded several years ago, meaning it’s now classified as a dwarf planet. But a recent meeting of the UK’s Royal Astronomical Society’s revealed some fascinating information about Pluto’s atmosphere, including that it’s made of carbon monoxide — a poisonous gas.

“The change in brightness over the last decade is startling,” University of St Andrews researcher Jane Greaves told Discovery News. “We think the atmosphere may have grown in size, or the carbon monoxide abundance may have been boosted.”

When analyzing the spectrum of the light reflected from this extended CO atmosphere, Greaves’ team spotted something odd. There’s a slight redshift in wavelength, indicating that the bulk of the gas is moving away from the Earth. Although the results are preliminary, Greaves has a theory.

“The marginal CO line red-shift, if real, could indicate a ﬂow forming into a comet-like tail directed away from the Sun,” she said.

Even though Pluto patrols the outermost region of the solar system, even this little world isn’t immune to the ravages of the solar wind, potentially turning it into a “comet dwarf.”